2015 October 4, William Wright, “A plan from Brussels where Britain can take the lead”, in The Telegraph‎[2]:

Whether you are a Europhile or a Brexiteer, it’s hard to see what’s not to like about a market-driven initiative that aims to pull down barriers to more investment across Europe.

2016 May 27, “David Cameron: I am not a closet Brexiteer”, in The Herald‎[3]:

Denying he was a "closet Brexiteer", as his former aide Steve Hilton has claimed, the PM told reporters: "I withdraw absolutely nothing I've previously said. Britain is an amazing country. We can find our way whatever the British people choose.

A leading Tory Brexiteer has insisted quitting the EU does not mean the numbers of people coming to Britain will be slashed - and claimed Vote Leave never said it would.

(politics, usually in the plural) Holder of any of the Cabinet posts tasked with negotiating exit from the European Union. (This is a hot sense, kept provisionally)

2016 July 14, Christian May, "May and the three Brexiteers lead Britain", City A.M..

Completing the Three Brexiteers is Boris Johnson, the UK's new Foreign Secretary.

2016 September 9, Simon Heffer, “The Three Brexiteers”, in New Statesman‎[5]:

For newspapers with only the Olympics to write about during August, the squabbling "Three Brexiteers" - the senior ministers supposedly tasked with executing the will of the British people to remove us from the European Union - came as a gift.

2016 October 2, Andrew Sparrow, “May says workers' rights will be protected as long as she is PM - Politics live”, in The Guardian‎[6]:

She urges people to get behind the team of ministers working for Brexit: David Davis, Liam Fox, Priti Patel and Boris Johnson. (It seems Patel has now been co-opted as a fourth Brexiteer.)

2016 October 31, Matt Chorley, “Bluster, bickering and three Brexiteers: stage is set for a satire made in heaven”, in The Times‎[7]:

That was until she announced that Boris Johnson would have to share Chevening, the foreign secretary’s grace-and-favour country retreat, with his fellow cabinet Brexiteers, David Davis and Liam Fox.

2017 June 11, Anoosh Chakelian, "Government reshuffle: who’s who in Theresa May’s new team?", New Statesman.

It's worth remembering all the Three Brexiteers, who campaigned to Leave, are still in place.